In a photo that popped up in mid April on the website hollabacknyc.com, two guys stand on a fire escape. The one smiling on the right is a blond wearing a black hoodie and white sneakers. The one on the left, in a baseball cap, glasses, and a T-shirt that reads "Texas Wins," has the fly down on his olive cargo pants. In his right hand, he holds his penis.

This is all we know for certain. Is Tex a jackass who is about to take a pissor a jackass who saw a pretty woman and willfully exposed himself? Did the woman who snapped the shot run to find her camera when she looked out her window and thought she saw two guys peeing? Or did the duo notice her first and feel inspired to get audacious, motivating her to pull a camera phone from her pocket to take revenge?

Because Holla Back's mission is to fight street harassmentby photographing catcallers and posting pictures on its sitewe are to assume the latter. Some other photos are accompanied by detailed accounts of offensive overtures, but here, a woman identified as "Shana" simply wrote, "Right out my third story window . . . this is SO annoying." Without much to go on, viewers must decide what's happening. As Marc Rotenberg, executive director of the Electronic Privacy Information Center (EPIC) points out, sites like Holla Back may open a door to misuse or defamation.

Internet and privacy experts are not surprised at the emergence of cyber-vigilantes like Holla Back. "Any human being with access to the Internet can pub
lish for free an image or text and have it accessed by anybody, anywhere in the world," notes John Palfrey, executive director of the Berkman Center for Internet and Society at Harvard Law. "But public awareness of the effect of that on your privacy rights hasn't caught up with the fact of the technology and the way people now use it."

Whether the guys are the libidinous and power-hungry types the group targets or jokers who decided it was a good idea to piss outside in broad daylight, it's tough to imagine what claims to privacy they might make. If the grandma of ol' Texas Wins is trawling the Internet one night and spots a photo of him on his fire escape, supporters of Holla Back ask, doesn't it serve Tex right?

"It's certainly true that people behave inappropriately, and enforcing norms is
difficult," says Daniel Solove, George Washington University Law School professor and author of The Digital Person. "On the other hand, doing something like this opens a Pandora's box of other problems." At a time when New York officials have just announced the installation of hundreds more cameras throughout the city, can surveil
lance via citizen be a positive development? Moreover, who watches the watchdogs when the watchdogs become avengers?

Sam Carter, one of Holla Back's founders, gets almost as animated talking about the camera phone technology that enabled Tex's online debut as he does about the notion of fighting street harassment itself. The technology Holla Back employs is easy to operate, cheap, and ubiquitous, and the decision to harness it for the site was a "no-brainer," Carter says. With one click, a woman can seize a kind of power usually unavailable to her by snapping a photo of the macho man on the sidewalk who moved in too close, saying, "Girl, I can smell you"to name one real-life example. With another click, she can send that photo to Holla Back, where Carter, the site's unofficial webmaster, and others upload it to the Web for worldwide viewing.

The power derived from witnessing, documentinginvading privacy even just a bitis typically associated with the federal government, the NYPD, and big corporations, Carter points out. Holla Back, says Carter, demonstrates that "you can fight the
oppressive network of surveillance by documenting things yourself. . . . We all can walk around with cameras as opposed to cops or government having them in the city."

There's a term in academia for the practice Carter describesUniversity of Toronto engineering professor Steve Mann coined it to mean the opposite of surveillance. "Sousveillance" is looking from below, turning the lens on the higher-ups, altering the power dynamic. For techie futurist types like Mann, the camera phone is just one stop on a fast train to the cameras all citizens will eventually wear on their heads, eyeglass-style; The Transparent Society author David Brin calls these devices "rodney kings."

Rodney King the person was assaulted by police officers, and Abu Ghraib, a more recent example of sousveillance, involved cameras that captured military abuses. With sites like Holla Backwhere citizens are schooling other citizens, not righting Big Brother's wrongscome questions of privacy, ethics, and the law that aren't getting answered as fast as the pace of newer and more sophisticated gadgets entering the market.

One well-publicized example of citizen-on-citizen sousveillancethe event
that inspired seven activists to create Holla Backoccurred when a Manhattan raw-food restaurateur was camera-phoned mid-masturbation on the subway last August by a woman who then posted the photo online. After the man was subsequently identified, one blogger wrote, "It's also good to see the Big Brother phenomenon (cameras everywhere you look) working out in the average citizen's favor for once . . . . What do you mean they're useless?! They can solve crimes!!"

Digital cameras do have the potential to generate a good-citizen award every now and then. But Bill Brown, founder of the anti-surveillance activist group Surveillance Camera Players, says sites like Holla Back illustrate the "lowest common denominator" effect of fighting cameras with cameras, instead of saying no to sousveillance or any other kind of surveillance, period. "It's never going to be a good thing," he says. "You're opening the floodgates to a universal degradation, reinforcing mutual suspicion and paranoia. I'm going through your trash, you're going through mine. I'm taking pictures of you, you're taking pictures of me. And all in the name of keeping people safe from some pretty soft crimes."

Though Holla Back encourages submissions from women outside New York City, it is based here, and it's not the only site in the city on which (unidentified) pictures of alleged lawless citizens appear. On her blog New York Hack, cab driver Melissa Plaut posts photos of her on-road antagonists and writes Holden Caulfield-esque tales to match. After one recent trying shift, Plaut wrote, "It can really make me crazy getting caught behind all these fuckfaces who don't know how to drive, and I sometimes find myself wishing I had something other than a camera to shoot them with."

The camera as weapon is a motif among privacy expertsMarc Rotenberg calls the tool that Holla Back promotes "photographic pepper spray."

But for others, it's more than self- defense. "It's a kind of vigilantism," warns Solove, "that falls beyond structures we've put up to deal with things in a more orderly or civil way. If you resort to this kind of activity you could be fighting lawlessness with another kind of lawlessness." Technically, snapping a shot of a stranger in public, even without that stranger's consent, is perfectly legal, unless said shot is used for commercial gain. Posting it to the Internet, a public space, is also within bounds. The so-called "up-skirt" laws recently passed in some statesas a result of the burgeoning practice of surreptitiously aiming a camera up the skirt or down the blouse of unsuspecting womenmake up one of the few exceptions. New York State decrees under "Stephanie's Law" that any such woman has a "reasonable expectation of privacy" in public.

Not so for a person who isn't exactly "unsuspecting," attracting attention by catcalling, for example, Rotenberg says; it's near impossible for that person to cry privacy invasion when someone takes his picture. If, however, a snapper puts online a photo that misrepresents or alters the truth, the same libel and defamation laws that apply to other media could come into play.

Raw-foodie Dan Hoyt, the subway flasher, recently complained to a New York magazine reporter about the effect on his privacy of his photo appearing online. Of course, "there's no legal protection that will leap in for that guy," Palfrey says; Hoyt actually pled guilty to public lewdness. But what if the name of the guy who did in fact flash it that day on the train was Texas Wins and not Dan Hoyt? Hoyt's name was floated on the Internet well before he was arrested. One man who posted to gothamist.com back then said it best: "Let me just get this out of the way first: If this guy Hoyt is not the one, God help us all for sullying the man's name."

Hoyt could have brought a tidy defamation case against the finger-pointers, had he not done the deed. Bill Brown, of Surveillance Camera Players, points out that even guilty people deserve due process. "If a picture is circulated in that fashion, people will believe the person guilty before he has been found so," Brown says. "A person could be tracked down, even beaten upand all of this will take place outside the normal channels."

But cyber-vigilantism may have more to do with violating an ethical or social "law" than an actual one. As a 2005 incident in South Korea illustrates, the biggest problem is the potential for a kind of punishment that outweighs the crime.

Last June, when a woman refused to clean her dog's mess from the subway floor in Seoul, South Korea, another commuter snapped and posted. After thousands viewed the photo, she was identified by her real name and subsequently dubbed "Dog Poop Girl" by Internet vigilantes. The woman and her family were harassed to such an extent that she reportedly dropped out of school and publicly threatened litigation and suicide.

Solove calls the effects of an embarrassing photo "permanent, like a kind of digital scarlet letter." He adds, "It's very problematic because there is a value to being able to live these things down. Eventually they're supposed to fade and be forgotten. It exacerbates the level of shame." Trying to remove an offending photo from the Web, a near-impossible endeavor, may draw even more attention to it.

Then there is the problem inherent to vigilantism of any stripe: unpoliced individuals doing the work of the police.

"Who makes sure they're acting appropriately?" says Solove. Citizens who become vigilantes, or "norm enforcers," can make a plausible case for what they're doing, "but what about when it's a norm you don't like? Anybody could decide to put up pictures of everyone who goes into a strip club, or abortion clinics, to make a point about abortion. What about a religious group that posts pictures of women wearing too provocative clothing?"

In legal circles, "the types of solutions that are fashionable right now involve harnessing the wisdom of the crowds to solve legal problems," Palfrey says. "But what if the wisdom of the crowd is wrong?"

To the Holla Back group, these kinds of objections are exhausting. "We're targeting a cultural institution, not persecuting one man," Carter says. "This is totally about the woman" and empowering her "to do something practical about an issue."

Like Carter, Plaut says she isn't going for an America's Most Wanted effect. For her, posting photos "is more about the beginning of why I started blogging: to say, this is what happened in my night. If I was just putting revenge pictures up, it would get boring."

Plaut says taking the picture is the end in itself. "Whether or not it goes on the blog doesn't matter," she says. "It's something I can do. I can't run them over, or get into a fistfight or take retributionI don't have time for that." Many of her photos anywhere from one to 20 per daydon't even make it online, she says.

The ill effects that most critics of this type of site caution against stem not from snapping a picture with a digital camera but from posting it before a potential audience of nearly 1 billion people.

Last August, when Plaut began blogging, she envisioned her site as a spot for friends to see photos from her shifts, inundated as she was with questions about what it's really like to drive a cab. So the decision to post a picture of a license plate belonging to a bad Jersey driverin that first month, when the site generated less than 50 hits per daywasn't difficult. "When I was still anonymous, it didn't bother me," says Plaut. "Recently I've been more concerned because my name is attached. What freed me to even do the blog was the anonymity and the fact that only people who knew me and liked me were going to be reading it."

Now, Hack gets hit anywhere from 4,000 to 9,000 times a day. "I try not to think about it," she says.

The small act of dealing with another individual takes on a life of its own when shared in the public space that is the Internet, and Holla Back knows this. While the group says snapping without posting is fine, in fact, "publishing is the keytestifying that this happened to you, publicly acknowledging it," says Emily May, one of Holla Back's other founders. "We're really interested in the place where the picture comes in, because that's what gets people's attention."

None of the stars of the Hack or Holla Back photo galleries have spoken up or complained about their pictures, according to Carter and Plaut (both of whom say they will take down a photo if need be, although once it's posted it may live forever). If undesirable consequences of the snap-and-post are expected to materialize, they haven't yet. And statistics for this kind of activitypeople claiming they've been marred by something on the Webaren't available in the U.S. But in South Korea, home to the unruly dog poop mob, incidents of cyber-violence have increased to such an extent (slander complaints to the Korea Internet Safety Commission reportedly tripled to 3,933 in 2005) that the government plans to require that citizens register for Internet use with full names and special cyberidentification numbers. So at least in South Korea, it will be everyone, not just wrongdoers, who is giving up some privacy.

South Korea, with the highest per capita rate of broadband Internet connections, is the most wired country in the world, and Palfrey cautions against drawing much of a parallel with the U.S.for one thing, the South Korean government is more heavily involved in subsidizing new technology and encouraging people to go online. But the link between person-to-person incidents of cyber-violence and government surveillance is noteworthy in light of Bill Brown's view that supporting any kind of citizen-on-citizen camera use contributes to the overall surveillance problem.

Whether or not all privacy activists agree with BrownRotenberg believes his stance is too extreme, though Brown pushes for some of the same surveillance restraints EPIC doesone thing is certain: The advancing technology is eroding privacy, and brothers both big and little are beneficiaries of your information.

Palfrey suggests attitude adjustment as a way to deal with it: "People should get smarter about managing their identities online and factor that into their decision-making process before they do something stupidor even not stupidbut something in public that could be broadcast to the rest of the world instantaneously."

While many privacy experts are fighting for a reversal of the trend, people like David Brin and Steve Mann are busy embracing it. For them, the embarrassment stemming from a photo beamed round the globe will be mitigated by the photo subject's ability to know the credit rating, criminal history, and bill of health of anyone who dares throw a stone.

"Is this a horrible future? Or actually a return to what we've always had in the past?" Brin says. "Think of old villages. Everybody knew everything about everybody else. Strangers were intimidating and worrisome. This will be like the village our ancestors grew up in, only with 7 billion people."

If not exactly an enticing prospect, it sheds light on the possible underlying reason for sites such as Hack and Holla Back: a need to cope with the reality of a city full of anonymous faces. "Street harassment happens in smaller communities, but you're not dealing with strangers," Emily May says. "In New York, you're dealing almost exclusively with strangers. Whistling at a girl in your gym class is different than whistling at a girl you're never going to see again."

There are other sites that have cropped up to deal with the perils of city life. After a bad landlord experience drove him to recount his woe online, one blogger invited others to post their own apartment nightmares, complete with details that clearly identify the targeted individuals. Unlike Hack and Holla Back, trembicky.com's modus operandi is printing first and last names, not photos, of people caught in the act of being bad landlords. But recent visitors to the site might have noticed a "bad real estate broker" story in the mixcomplete with a head shot of the allegedly offending professional.

So now it's do the crime, do the face time. Or as one blogger wrote about the dog poop saga: "Maybe now technology will provide a way to reinstate that societal feedback. I doubt this episode would have occurred in a small town where everyone knows everyone and such actions would have resulted in immediate consequences."

In a small town, "visual stocks"what Amanda Lenhart, a researcher for the Pew Internet & American Life Project., calls sites that put wayward citizens on display, as did those wooden structures of long agojust might not be necessary.

The problem, as it always was, is just who gets put in the stocks and why.